The Earth From The Moon

The Earth as seen from the Moon! LROC NAC mosaic of images snapped on 12 June 2010 during a calibration sequence.All cameras are susceptible to scattered light. You may have seen scattered light in pictures you have taken looking towards the Sun. Sunlight reflects off the optics and sometimes off the structure of the lens, and often appears as a gradient of brightness across the image.Attaching a baffle to your camera, like we did with the LROC Wide and Narrow Angle Cameras, can minimize this effect.

More subtle effects are often present but usually you simply just don't notice artifacts because of strong color contrasts in the scene. Since the Moon has only very small color contrasts, the LROC team must characterize even subtle scattered light effects within the 7-color Wide Angle Camera (WAC) images. Changes in composition result in subtle differences of color, typically about 10% or less. For scientists to make accurate interpretations of WAC color maps, the amount of scattered light must be quantified.

One way of measuring scattered light is imaging a bright object against a dark background.From the Moon, the Earth serves that function well. While a series of WAC calibration images of the Earth were being acquired, the Narrow Angle Camera (NAC) was shuttered to capture this spectacular Earth view. The bottom of the Earth was clipped because the prediction of the exact time when the cameras' fields of view would cross the Earth was off by a few seconds.